Can you actually change the past so that an event never happened?
It's truly a matter of perception. I can go there by merging with a your timeless consciousness and travel beyond time to adjust things, ie, shift perceptions. Perception does create—and change—reality. This process sets in motion a wave of change that flows into the present and future. This also helps to neutralize the negative residue that you carry when you live with regret.
It's often a powerful process for clients in consultations when I personally escort them back to the past event. I invite them to make a different choice. It's the opportunity to respond differently, to make the decision that they desperately long to have made, rather that the one that's left them living with so much regret.
From that juncture in the past, we travel together down a new and different path, experiencing a different outcome, feeling the contrast, new sensations and emotions resulting from a different choice. In a sense, we're creating an "alternate reality."
Finally, I encourage the client to meditate on that new and different outcome every day, for at least thirty days, to go into a quiet state and repeat the walk down that alternate road...remember and re-experience it all...embrace it all...feel it in their bones.
This will bring about a "bleedhrough" effect that will flow into this third dimension reality. Life will start to feel different in the present—and the past will exist in a new way. Optimism replaces regrets with a sense of freedom, releasing you from the past into a new present. From there you can now face forward towards your best, most positive future.
We all have had experiences in the past that we'd like to erase. I personally believe that the soul evolves more expediently when we focus on the wisdom is gained (usually in retrospect) from the "mistakes," rather than from searching for a fourth-dimensional "wormhole" through which to crawl back through time, and somehow "make it so that it never happened." Living with regrets is an issue that's important to address in itself. Like fear, it's a contracting perception. I lowers your vibration. It doesn't let in much Light.